Shulkers riding on another Entity appear in the middle of the Entity

How to reproduce:

Summon an Armor Stand with an Shulker ontop.
/summon armor_stand ~ ~2 ~ {Tags:["eliv"],Passengers:[

{id:"minecraft:shulker",NoAI:1b,AttachFace:0b,Color:4b,Tags:["eliv"]}

]}

as you can see the Shulker is in the middle of the Armor Stand

now summon an Armor Stand with an falling Block ontop:
/summon armor_stand ~ ~2 ~ {Tags:["eliv"],Passengers:[

{id:"minecraft:falling_block",Time:1,Tags:["eliv"]}

]}

as you can see the falling Block is on the Head.